1. Field of the Invention
This invention relates to firearms generally, and particularly relates to a breech-loading, repeating bolt action rifle.
2. Description of the Prior Art
A bolt action rifle is a firearm which is defined by the mechanism used to insert cartridges into the firing chamber. Most rifles have a magazine for the storage of cartridges from which cartridges are stripped under spring pressure, one at a time, for insertion into firing position. While being stripped, and once stripped, the cartridge round in a bolt action rifle is impelled forward by a structure called the bolt. The bolt is generally hand operated by the user.
A breech loading rifle is defined as a firearm in which a cartridge is loaded into the rear of the barrel.
The literature and history relating to breech loading bolt action rifles is both extensive and complex. The rifle models manufactured by Paul Mauser as the Mauser Model 1898 have achieved special fame and are described in an article "The Mauser Rifle Story" by Jon Sundra, Guns & Ammo, September, 1985, and by "The Bolt Action", by Stuart Otteson, Volume I, Wolfe Publishing Co. Inc., ISBN 0-935632-21-2, 1976.
U.S. Pat. No. 3,835, 566 to Bielfeldt et al. is descriptive of a bolt action rifle.
The Sundra article, on page 52, describes a problem called "double loading". Many bolt action designs allow that the cartridge is not under direct control by the bolt during insertion but rather the cartridge is merely pushed forward toward the firing chamber. If for any reason, such as panic, the operator fails to fully insert the cartridge by complete and proper travel of the bolt, it is possible to leave an unspent cartridge in the rifle and to reverse the bolt ("short stroking") to return to strip out a second cartridge from the magazine. When the bolt is used to insert the second cartridge, the point of the second cartridge encounters the rear of the first unejected cartridge and may detonate the first cartridge or may merely jam the loading mechanism.
The double loading problem was recognized by Paul Mauser and corrected in his design known as the Spanish Mauser 1891. This rifle provided for a bolt which rotated about its axis prior to movement longitudinally toward and away from the firing chamber. At the rearmost position of the bolt, the bolt face stops behind the magazine. The bolt has an undercut bolt head rim which receives the cartridge rim. A non-rotating extractor captures the cartridge after it jumps free of the magazine. Thus, if the bolt is drawn rearward at any time, it pulls the cartridge with it and ejects the cartridge normally from the rifle before a new cartridge is stripped from the magazine. This mechanism effectively prevents double loading malfunctions.
The Mauser 1891 design introduced a new problem in exchange for the elimination of double loading. The undercut to the face of the bolt leaves a portion of the cartridge unsupported during firing.
It is usual to manufacture cartridge cases of brass, a material which has insufficient strength to withstand the gas pressures generated by the detonation of the cartridge. The cartridge expands during detonation and bears against the stronger steel surfaces which surround it, generally that of the bolt face and the barrel. In the direction of the barrel axis, gas pressure is relieved by propelling the rifle bullet forward.
In the area of the undercut of the bolt face, a portion of the cartridge rim is not supported. That is, the cartridge must expand excessively to encounter support steel. This lack of support results in occasional cartridge rupture, producing a flux of brass particles and high pressure gas through the mechanism of the rifle and outward via available clearances.
Efforts to more effectively seal the breech involved decreasing the area of nonsupport by decreasing the bolt rim height or by milling projections from the rear of the barrel. This resulted in a decrease of feeding reliability and/or involved complex machining and difficult fitting of breech components. Because of the otherwise extreme reliability, the basic design of the Mauser rifle bolt and extractor were closely imitated by military bolt action rifles. Many commercial rifles, in contrast, use fully-enclosing bolt faces which combine with the barrel to fully enclose the cartridge during firing. These rifles do not preclude double loading.
An object of this invention is to provide a bolt action rifle design which simultaneously allows for controlled round feeding to prevent double loading and for a fully supported cartridge to help prevent and contain a cartridge rupture, resulting in increased reliability and safety.